1. Field of the Invention
The present invention relates to an image processing method and system. More specifically, the invention relates to an image processing method and system that performs optimal color density decomposition.
2. Description of the Related Art
There are many different types of known data output systems such as word processors, personal computers, and facsimile devices. Among these known data output systems is an ink jet printer, which records text and images on a recording medium by discharging a colorant onto the recording medium. The performance of inkjet printers has been improved recently and these inkjet printers are capable of high quality recording of, not only text, but also color images.
An inkjet printer records intermediate tones of color by controlling the spatial distribution of ink dots discharged from printer heads. However, for regions with a low dot concentration, i.e., the highlights of the image, the dots appear grainy.
Japanese Patent Laid-Open No. 2002-059571 discloses a system for reducing the graininess of highlights by using light-colored ink (light cyan (Lc) and light magenta (Lm)) in addition to the basic four colors: cyan (C), magenta (M), yellow (Y), and black (K).
Specifically, cyan is separated into a light cyan (Lc) ink and a dark (regular) cyan (C) ink, a process referred to as ‘color density decomposition.’ Color density decomposition is based on empirical assumptions that “the lighter the background, the more the dark cyan stands out” and that “it is better to use light colored ink in the vicinity of the highlight.” However, graininess of the printed images is not always reduced indicating that optimal color density decomposition has not been achieved.